umm, you can get a new motherboard, then windows will want you to reinstall, and a motherboard replacement is about as much work as building a new computer because you have to remove just about everything (but its cheaper)

if you want to do that just make sure to get a board that has the same CPU socket and ram type, and i recommend http://newegg.com/

Also, check out devhardware and use Google to find information and tutorials. Overclocking is a lot of fun, and can be a great way to improve your computer's performance, but it also stresses components and voids warranties.
Not to be elitist, but if you have to ask how to even try to OC, you probably aren't prepared to do it. Once you learn a little more about computer hardware, you'll be able to figure out a lot on your own, and use resources like this forum to iron out the kinks